Mike Klis of The Denver Post reported Sunday that the Broncos offered Clady a five-year, $50 million contract extension with $28 million guaranteed, according to an NFL source.

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The sides began talks on a new deal in May. If Clady accepts the offer, he would become one of the five richest offensive linemen in football, based on annual salary. The $10 million rate would be a substantial bump from the $3.5 million he is scheduled to earn in 2012.

Selected with the No. 12 overall pick in the 2008 NFL Draft, Clady has started all 66 regular-season and playoff games during his career. He has missed just 15 regular-season snaps over his four-year career. Clady earned All-Pro honors as a rookie and went to the Pro Bowl following the 2009 and 2011 seasons.

If the sides can't come to an agreement -- and The Post reported that Clady wants slightly more than Cleveland Browns left tackle Joe Thomas' $11.5 million per year -- the Broncos still have the fallback option of using the franchise tag next season. Young linemen of Clady's caliber typically are locked up before they sniff the open market, and that certainly seems to be the Denver Broncos' plan here.